The ever increasing functional range of present-day devices leads to well known compatibility problems. On the one hand, there is a demand for an increasing functional range, whereas, on the other hand, there is a demand for supporting also older devices. This applies also to the communication between a data carrier and a reader device, which this invention is about. Data carriers are widespread, e.g. in the form of smart cards. Nearly everyone carries a number of smart cards, e.g. access cards, credit cards, loyalty cards, etc., so that there are a lot of smart cards in circulation. More and more data is stored on such data carriers, which leads to problems when use is made of a communication protocol which was designed for a low amount of data. Quite often it turns out that the data rate which was considered to be sufficient in the past, does not fit current demands. So, there is a need for modern, fast communication protocols for data carriers on the one hand, whereas the original communication protocol should be supported as well on the other hand. Hence, a negotiation procedure is needed to decide which communication protocol is to be used. However, this change should be made without influencing the present reader device/smart card infrastructure if possible, which is not an easy task, as data carriers normally have an interface tailored for the original demands, but not for present and future demands. Accordingly, there is normally only a limited number of contacts which may be used for negotiating a communication protocol. One example for an existing data carrier is a smart card compliant with ISO 7816, which today has an interface with eight contacts and a communication protocol for low data rates. One example of an existing (low data rate) protocol is the T=0/T=1 isochronous protocol within the frequencies allowed in ETSI TS 102 221 “Smart Cards; UICC-Terminal interface; Physical and logical characteristics”. However, these are just particular examples taken from a vast number of examples. A person skilled in the art will easily understand that it is not possible to provide a complete list of examples and that the problems stated above apply to various other data carriers as well.
It is thus an object of the invention to provide a solution for negotiating a proper communication protocol between a data carrier and a reader device with little or no influence on an existing infrastructure.